1. Field of the Invention
This invention relates to an ophthalmologic phototaking apparatus capable of outputting the image of an eye to be examined as a digital signal.
2. Related Background Art
There is known an ophthalmologic phototaking apparatus system in which a TV camera having an analog image signal output is connected to an ophthalmologic phototaking apparatus body to thereby phototake the image of an eye to be examined and an analog image signal obtained can be outputted to a surrounding apparatus. However, the system outputting an analog image signal is weak against disturbance and suffers from the disadvantage that deterioration occurs to the image before diagnosis.
So, in recent years, use has generally been made of an ophthalmologic phototaking system in which a digital camera having a digital image signal output is connected to an ophthalmologic phototaking apparatus body and a digital image signal obtained with the phototaken image of an eye to be examined can be outputted to a surrounding apparatus such as an image recording apparatus. There is also known an ophthalmologic phototaking system which can output phototaking condition information and information relating to an eye to be examined such as patient information from output means differing from an image signal output means.
There is further known an ophthalmologic phototaking apparatus in which an electronically phototaken image is converted into digital data and is transferred to the outside and recorded on a portable type recording medium, and the rate of image compression is preselected before a series of phototaking operations are performed, and the image is compressed in conformity with the compression rate and is recorded on a recording medium.
(1) However, in the ophthalmologic phototaking apparatus according to the above-described example of the conventional art, the data of the digital image signal outputted from the digital camera adopts a form in which the information of each pixel is simply outputted, and the size of the image, the amount of information in the direction of harmony and the kind of the image such as whether the image is a colored image differ from one type of machine to another and therefore, the form of the outputted data is unique to the type of machine. Therefore, the surrounding apparatus receiving the digital image signal output must prepare exclusive data converting means in conformity with the type of the digital camera. Accordingly, the surrounding apparatus is limited to exclusive use with the ophthalmologic phototaking apparatus and has not the interchangeability with other diagnosis systems in the hospital, and this leads to the problem that the ophthalmologic phototaking apparatus becomes an ophthalmologic phototaking apparatus system of low flexibility.
(2) Also, the apparatus designed such that the compression rate of the image is set by outside recording means has the problem that it is difficult to set the compression rate in the course of a group examination or in the course of the fluorescent retinal phototaking operation and setting is liable to be forgotten because the setting conditions cannot be confirmed. Further, the eye fundus camera body is not provided with means for detecting the image compression information to be phototaken from now on and therefore, in spite of the information being lost by image compression, a light brighter than necessary is applied to the eye to be examined and phototaking is effected with a low gain in order not to deteriorate the S/N ratio. Also, the current image is not preserved for generally non-reversible image compression, and this leads to the problem that re-compression cannot be done and the quality of image as a further compressed result cannot be confirmed on the spot.
(3) Further, the information relating to the eye to be examined and the image signal of the eye to be examined are outputted from discrete means at different timings and therefore, there is the possibility that the discordance of data that the information relating to the eye to be examined and the image information do not coincide with each other may occur.
(4) Also, when the digital signal is outputted, there are present numerous different data forms for communication and output means which prescribe the communication speed, the input and output terminals and the communication form such as either serial or parallel, and this leads to the problem that great limitations are given to the surrounding apparatus.